It is known to use a fluid flow control valve in an automotive cooling system to regulate the flow of coolant and thereby regulate the operating temperature of the engine of the automobile.
One class of conventional fluid flow control valves for automotive cooling systems employs a wax element that is sensitive to coolant temperature to regulate the opening and closing of the fluid flow control valve thereby regulating the flow of coolant through the automotive cooling system. However, due to the nature of the wax element, this type of system is slow to respond to changes in the temperature of the engine. Furthermore, since the opening and closing of the valve is controlled by the thermal properties of the wax used in the valve, the operating temperature range in which the engine is controlled cannot be easily adjusted.
Another type of fluid flow control valve for an automotive cooling system provides a desired rate of coolant flow using an electrically-operated valve that is driven to a desired position, for example, by a stepper motor.
Another type of fluid control establishes and blocks fluid flow using a pressure-operated diaphragm valve that moves in response to pressure in a control chamber. The pressure in the control chamber is regulated by an electrically operated valve that is much smaller in size as compared to the diaphragm valve. In these valves, the pressure-operated diaphragm valve moves between fully open and fully closed positions is correspondence with opening and closing of the electrically operated valve.